What causes angina

Overview

Angina, often referred to as angina pectoris, is a type of chest pain or discomfort that occurs when the heart muscle doesn't get as much oxygen-rich blood as it needs. This typically happens during periods of increased demand on the heart, such as during physical activity or emotional stress. While it's often described as a symptom, angina itself is a sign of an underlying problem, most commonly coronary artery disease (CAD).

What is Coronary Artery Disease (CAD)?

Coronary artery disease is a condition characterized by the narrowing or blockage of the coronary arteries, the blood vessels that supply the heart muscle with blood. The primary culprit behind this narrowing is atherosclerosis, a gradual process where fatty deposits, cholesterol, and other substances, collectively known as plaque, build up on the inner walls of the arteries. Over time, this plaque can harden and narrow the arteries, restricting blood flow. When the coronary arteries become significantly narrowed (usually by more than 70%), the heart muscle may not receive enough oxygen, especially when it has to work harder.

The Mechanism of Angina

When you engage in physical activity, experience stress, or face other situations that increase your heart rate and blood pressure, your heart muscle requires more oxygen. If the coronary arteries are narrowed due to atherosclerosis, they cannot dilate sufficiently to deliver the extra oxygenated blood needed. This mismatch between oxygen supply and demand leads to the characteristic chest pain or discomfort of angina. The pain is often felt as a pressure, squeezing, tightness, or aching in the chest, and it can sometimes radiate to the arms, neck, jaw, or back.

Types of Angina

Angina is broadly categorized into different types based on its pattern and cause:

• Stable Angina: This is the most common type. It occurs predictably when the heart is working harder, such as during exercise or stress. The pain is usually relieved by rest or medication like nitroglycerin. Stable angina typically follows a consistent pattern for months or years.
• Unstable Angina: This is a more serious condition and a medical emergency. It can occur at rest, without exertion, and the pain may be more severe or last longer than usual. Unstable angina can also occur with a new pattern of symptoms or a worsening of previous symptoms. It indicates a sudden, dangerous reduction in blood flow to the heart, often due to a plaque rupture and blood clot formation.
• Variant Angina (Prinzmetal's Angina): This is a rare form of angina caused by a spasm of the coronary artery, which temporarily narrows the artery and reduces blood flow. It often occurs at rest, typically during the night or early morning, and can cause severe chest pain.
• Microvascular Angina: In this type, the small blood vessels that branch off the coronary arteries are affected. While the large coronary arteries may appear normal on tests, the small vessels may not function properly, leading to reduced blood flow and angina symptoms.

Factors Contributing to Angina

Several factors can increase the risk of developing atherosclerosis and, consequently, angina:

• Atherosclerosis: As mentioned, the buildup of plaque in the coronary arteries is the leading cause.
• Coronary Artery Spasm: In rarer cases, the coronary arteries can constrict (spasm), reducing blood flow. This can occur independently or in conjunction with atherosclerosis.
• Other Medical Conditions: Conditions like high blood pressure (hypertension), high cholesterol (hyperlipidemia), diabetes, and obesity can accelerate atherosclerosis.
• Lifestyle Factors: Smoking, a lack of physical activity, an unhealthy diet, and excessive alcohol consumption are significant contributors.
• Genetics and Age: A family history of heart disease and increasing age are also risk factors.

When to Seek Medical Attention

If you experience chest pain or discomfort, it's crucial to seek medical advice promptly. If your symptoms are new, worsening, or occur at rest, call emergency services immediately, as this could indicate unstable angina or a heart attack. A healthcare professional can diagnose the cause of your angina through a physical examination, medical history, ECG, stress tests, and other diagnostic procedures, and then recommend the appropriate treatment plan.